A hemodialysis apparatus comprises a dialysate side and a blood side. The dialysate side includes a dialysate source supplying the dialysate, either in the form of dialysate water mixed with additives by the hemodialysis apparatus or in the form of a dialysis supply. The dialysate chamber of a dialyzer with a membrane and a dialysate pump pumping the dialysate from the dialysate source to the dialysate chamber are further included on the dialysate side. Finally, a waste pump is provided on the dialysate side between the dialysate chamber and a waste tank or a waste discharge. The blood side includes the blood chamber of the dialyzer as well as a venous line and an arterial line which are connected to a respective one of the two ends of the dialyzer blood chamber.
A pre-filling liquid source is further provided which supplies the pre-filling liquid for pre-filling the venous and arterial lines. The pre-filling liquid source can be formed by the dialysate source, but may basically also be a separate pre-filling liquid source, for example, a bag containing a saline solution.
Prior to applying the venous and arterial lines or the respective cannulas to a patient, the two blood-side lines are pre-filled with pre-filling liquid, as is described, for example, in DE 196 55 224 B4. The introduction of the pre-filling liquid can be supported by a pump, for example, by the dialysate pump, which generally is configured as a displacement pump in the form of a peristaltic hose pump. There is therefore an inherent risk that, during the pre-filling, the fluid pressure in the venous and/or the arterial line increases to an extent, for example, because of a kinked line, that unallowable overpressures occur or the relevant line can be damaged and thereby become leaky. If the leak initially goes unnoticed, the effort in preparing the dialysis can increase substantially.